Remove Emscripten support

test/CodeGen/JS/alloca-contradiction.ll

-; RUN: llc < %s
-
-; In theory, the @llvm.lifetime intrinsics shouldn't contradict each other, but
-; in practice they apparently do sometimes. When they do, we should probably be
-; conservative.
-
-target datalayout = "e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-p:32:32:32-v128:32:128-n32-S128"
-target triple = "asmjs-unknown-emscripten"
-
-; Don't merge these two allocas, even though lifetime markers may initially
-; appear to indicate that it's safe, because they also indicate that it's
-; unsafe.
-
-; CHECK: foo
-; CHECK: HEAP8[$p] = 0;
-; CHECK: HEAP8[$q] = 1;
-define void @foo() nounwind {
-entry:
-  %p = alloca i8
-  %q = alloca i8
-  br label %loop
-
-loop:
-  call void @llvm.lifetime.end(i64 1, i8* %q)
-  store volatile i8 0, i8* %p
-  store volatile i8 1, i8* %q
-  call void @llvm.lifetime.start(i64 1, i8* %p)
-  br i1 undef, label %loop, label %end
-
-end:                                              ; preds = %red
-  ret void
-}
-
-declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
-declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind